An example of a solid-state laser is disclosed, for example, in EP1178579A2. In that example, in order to discharge heat from a plate-like solid body to a heat sink (known as the cooling body), it is proposed that the side of the plate-like solid body facing the heat sink be mechanically and thermally coupled to the carrier face formed on the heat sink by an adhesive layer. The adhesive layer is produced from an adhesive which changes from a fluid state into a solid, cross-linked state in a substantially volume-invariable manner. The adhesive layer has an active adhesive layer region with a thermal resistance of less than 10 K mm2/W. This solution is intended to ensure that the solid body is fixed to the heat sink securely and without significant mechanical deformations and that no reduction of the heat flow from the solid body into the heat sink occurs as a result of the adhesive layer.
A solid-state laser arrangement as described above is suitable for producing high laser powers in the kilowatt range. Owing to the small thickness of the plate-like solid body, however, when the laser medium is pumped with a single pass of pump radiation, only a little pump radiation is absorbed. In order to increase the efficiency of such a solid-state laser arrangement, the pump radiation can be redirected several times and reflected back to the plate-like solid body. In this instance, the pump radiation can be focused several times, for example, at a parabolic mirror onto the plate-like solid body, as described, for example, in DE 100 05 195 A1. Owing to the multiple redirections, a laser power of approximately 2 kW or more can be produced.
With such high power of the laser radiation, the plate-like solid body or the laser-active solid-state medium, despite the cooling, is placed under a high thermal load. Since the pump radiation is generally focused only in a portion of the entire volume on the plate-like solid body, the pump radiation field, and consequently also the heat produced, is concentrated on this portion of the volume, whereas, in an edge region of the plate-like solid body, the coupled pump output or the pump radiation field is significantly weaker. Owing to the differences in the strength of the pump radiation field and accordingly also the laser radiation field produced in the active laser medium, significant thermal loads occur particularly in the edge regions of the plate-like solid body and may lead to erosion of the solid-state medium in the edge regions and may consequently lead to an impairment of the effectiveness of the solid-state laser arrangement and potentially to complete failure of the solid-state laser arrangement.